Pregnant or over reacting!?

Ok so two months ago in April me and my boyfriend had sex and didn't use a condom for a few minutes and he didn't cum in me either the next month my cycle was light and only for three days when it's usually heavy and goes for 7 days and it happened again this month I took two tests and they both said they were negative but in afraid I didn't do it right I haven't had any symptoms like cravings, tender/swollen breasts or morning sickness please help cause idk if it's my BC that messes up my cycles (Copper IUD) or I was just super stressed and at the same time my boyfriend came home I stopped my healthy diet that was going for a few weeks